1. Field of the Invention
The invention relates to a method and apparatus to twist at least two running threads about each other.
Methods and apparatus to twist at least two moving threads about each other are used on twisting devices to twist threads. Furthermore methods and apparatus to twist at least two moving threads are used in weaving machines to form a selvage weave, with at least two selvage threads being twisted around each other and filling threads being inserted between them. In this manner a selvage or a waste edge will be made.
2. Description of the Related Art
In a known weaving machine selvage forming device (U.S. Pat. No. 4,478,256), reciprocating thread guides are used. A first kind of thread guide consisting of a needle with a thread eye is employed to guide a first selvage thread. Moreover, a second thread guide is employed, consisting of two elements fitted with diagonally opposite slits to guide a second selvage thread. The two thread guides are moved oppositely to each other in order to build a shed from the selvage threads. Also, the two elements of the second thread guide are simultaneously moved in mutually opposite directions with a slight gap between the elements to implement a lateral motion of the selvage thread that is guided through the slits. Such selvage forming devices employ reciprocating thread guides that cause excess noise and vibrations that arise from the additional wear in the drive device of the thread guides.
Another design for a selvage forming device (U.S. Pat. No. 3,880,199) provides a rotating disk with a pair of thread-guiding eyes that are situated diametrically opposite one another, with the axis of rotation positioned between the eyes and each eye guiding one selvage thread.
Another apparatus (French patent document A 2,095,367) uses a pair of eyes oppositely connected to an endless, driven belt, with each eye guiding one selvage thread, to form selvages or waste strips, with the belt driving the eyes substantially synchronously with the weaving machine's shed-forming device.
It is also known (as in British patent 819,583) to false-twist two or more threads and to wind them on a spool. As each of the threads is guided through an axial hole of a toothed wheel, the threads are twisted when the toothed wheel is driven in alternating directions of rotation.